The electricidal effect: reduction of Staphylococcus and pseudomonas biofilms by prolonged exposure to low-intensity electrical current.
The activity of electrical current against planktonic bacteria has previously been demonstrated. The short-term exposure of the bacteria in biofilms to electrical current in the absence of antimicrobials has been shown to have no substantial effect; however, longer-term exposure has not been studied. A previously described in vitro model was used to determine the effect of prolonged exposure (i.e., up to 7 days) to low-intensity (i.e., 20-, 200-, and 2,000-microampere) electrical direct currents on Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis biofilms. Dose- and time-dependent killing was observed. A maximum of a 6-log(10)-CFU/cm(2) reduction was observed when S. epidermidis biofilms were exposed to 2,000 microamperes for at least 2 days. A 4- to 5-log(10)-CFU/cm(2) reduction was observed when S. aureus biofilms were exposed to 2,000 microamperes for at least 2 days. Finally, a 3.5- to 5-log(10)-CFU/cm(2) reduction was observed when P. aeruginosa biofilms were exposed to electrical current for 7 days. A higher electrical current intensity correlated with greater decreases in viable bacteria at all time points studied. In conclusion, low-intensity electrical current substantially reduced the numbers of viable bacteria in staphylococcal or Pseudomonas biofilms, a phenomenon we have labeled the "electricidal effect."
del Pozo
Jose L
JL
Division of Infectious Diseases, Infectious Diseases Research Laboratory, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
Rouse
Mark S
MS
Mandrekar
Jayawant N
JN
Steckelberg
James M
JM
Patel
Robin
R
D001372:Aza Compounds / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D004560:Electricity / Q000009:adverse effects*; D024841:Fluoroquinolones; D000077266:Moxifloxacin; D011549:Pseudomonas / Q000187:drug effects / Q000254:growth & development*; D011804:Quinolines / Q000494:pharmacology; D013210:Staphylococcus / Q000187:drug effects / Q000254:growth & development*; D014031:Tobramycin / Q000494:pharmacology
D001372:Aza Compounds; D024841:Fluoroquinolones; D011804:Quinolines; D000077266:Moxifloxacin; D014031:Tobramycin